1. Field of the Invention
The present invention relates to an electron-beam generator capable of emitting electron beams in accordance with information signals. It also relates to an image display apparatus making use of the electron-beam generator.
2. Related Background Art
In the art, there are thin-gage image display apparatus comprising a plurality of electron-emitting devices arranged in a plane form and fluorescent member targets individually receiving irradiation of electron beams from the electron-emitting devices, both of which are respectively face-to-face.
These electron-beam image display apparatus basically have the following structure.
FIG. 11 is an exploded perspective view to schematically illustrate a conventional display apparatus. The numeral 1 denotes a rear plate; 2, a support; 3, a wiring electrode; 4, an electron-emitting area,; 5, an electron-passing aperture; 6, a modulating electrode; 7, a glass plate; 8, a transparent electrode; and 9, an image forming member, which comprises a member capable of emitting light, causing a change in color, being electrically charged, and causing a change in properties as a result of impingement of electrons, as exemplified by a flurorescent member and a resist material. The numeral 10 denotes a face plate; and 12, a luminescent spot. The electron-emitting area 4 is formed by a thin-film technique, and constitutes a bridge structure so that it may not come into contact with the rear plate 1. The wiring electrode 3 may be formed using the same materials as those for an electron-emitting member, or using different materials. Those having high melting point and small electrical resistivity are commonly used. The support 2 is formed of an insulating material or a conductive material.
In these electron-beam image display apparatus, a voltage is applied to the wiring electrode 3, so that electrons are emitted from the electron-emitting area that constitutes the hollow structure, and electrons are taken out by applying a voltage to the modulating electrode 6 capable of modulating a flow of the electrons thus emitted, in accordance with information signals, and the electrons thus taken out are impinged against the fluorescent member 9. An XY matrix is also formed by the wiring electrode 3 and the modulating electrode 6, and thus an image is displayed on the image forming member, i.e., the fluorescent member 9.
The above conventional electron-beam image display apparatuses have the following problems:
(1) Since the modulating electrode 6 is disposed above an electron-emitting device (comprised of the support 2, the wiring electrode 3 and the electron-emitting area 4) and in the direction of the emission of electrons as shown in FIG. 11, the electron-passing aperture 5 of the modulating electrode 6 and the electron-emitting area 4 can be difficult to aligned with each other. Hence, it is difficult to manufacture a wide-screen image display apparatus with high definition. PA0 (2) Since both the modulating electrode 6 and the electron-emitting area 4 of the electron-emitting device are disposed in such a way that a space is given between them as shown in FIG. 11, the distance between the modulating electrode 6 and the electron-emitting area 4 of the electron-emitting device can not be kept uniform. In particular, in the case when a plurality of electron-emitting devices are provided, the distances between all the electron-emitting areas and modulating electrode(s) can be made uniform with difficulty. Hence, it is difficult to manufacture a wide-screen, highly detailed image display apparatus. PA0 (3) An attempt to manufacture the wide-screen, highly detailed image display apparatus may result in a serious luminance non-uniformity of a displayed image.
FIG. 12 shows another example of the conventional electron-beam image display apparatus. In FIG. 12, the numeral 21 denotes a substrate; 22, a modulating electrode; 23, a thermoelectron beam source; 24, an upper deflecting electrode; 25, a lower deflecting electrode; and 26, a face plate provided with a transparent electrode and an image forming member, which is capable of emitting light, causing a change in color, being electrically charged, and causing a change in properties as a result of impingement of electrons, as exemplified by a fluorescent member and a resist material. The thermoelectron beam source comprises a tungsten wire coated with an electron-emitting material, and has an outer diameter of about 35 .mu.m and an operation temperature of from 700.degree. to 850.degree. C.
In the conventional electron-beam image display apparatus as shown in FIG. 12, the modulating electrode 22 is disposed on the side opposite to the direction of electron emission, of the thermoelectron beam source (an electron-emitting device) 23. Hence, although the above problem (1) can be eliminated, the above problems (2) and (3) can not be eliminated.